/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/

#include "tensorflow/compiler/mlir/tools/kernel_gen/tf_gpu_runtime_wrappers.h"

#include <string>

#include "absl/container/flat_hash_map.h"
#include "absl/strings/str_cat.h"
#include "tensorflow/compiler/xla/stream_executor/stream.h"
#include "tensorflow/compiler/xla/stream_executor/stream_executor_internal.h"
#include "tensorflow/core/platform/logging.h"
#include "tensorflow/core/platform/mutex.h"

static void ReportInternalError(tensorflow::OpKernelContext *ctx,
                                const std::string msg) {
  if (ctx == nullptr) {
    LOG(WARNING) << msg << "\n";
    return;
  }
  ctx->CtxFailureWithWarning(
      tensorflow::Status{absl::StatusCode::kInternal, msg});
}

#if GOOGLE_CUDA
using GPUResult = CUresult;
#endif
#if TENSORFLOW_USE_ROCM
using GPUResult = hipError_t;
#endif

void GPUReportIfError(GPUResult result, tensorflow::OpKernelContext *ctx,
                      const char *expr_str) {
  if (!result) return;
  const char *name = nullptr;

#if GOOGLE_CUDA
  cuGetErrorName(result, &name);
#endif
#if TENSORFLOW_USE_ROCM
  name = hipGetErrorName(result);
#endif

  if (!name) name = "<unknown>";
  std::string msg = absl::StrCat("'", expr_str, "' failed with '", name, "'");
  ReportInternalError(ctx, msg);
}

#define GPU_REPORT_IF_ERROR_WITH_CTX(expr, ctx) \
  GPUReportIfError(expr, ctx, #expr)
#define GPU_REPORT_IF_ERROR(expr) GPU_REPORT_IF_ERROR_WITH_CTX(expr, nullptr)

// Implement the GPU module cache and share what can be shared.

namespace mlir {
namespace kernel_gen {
namespace tf_framework {

GPURuntimeCache::~GPURuntimeCache() {
  tensorflow::mutex_lock lock(mu_);
  for (auto it : gpu_module_by_data_ptr_) {
#if GOOGLE_CUDA
    GPU_REPORT_IF_ERROR(cuModuleUnload(it.second));
#endif
#if TENSORFLOW_USE_ROCM
    GPU_REPORT_IF_ERROR(hipModuleUnload(it.second));
#endif
  }
}

tensorflow::Status GPURuntimeCache::Create(GPURuntimeCache **dst) {
  *dst = new GPURuntimeCache;
  return ::tensorflow::OkStatus();
}

std::string GPURuntimeCache::DebugString() const { return "GPU runtime cache"; }

GPURuntimeCache::GPUModule GPURuntimeCache::LookupOrLoadModule(void *data) {
  tensorflow::mutex_lock lock(mu_);
  GPUModule &module = gpu_module_by_data_ptr_[data];

#if GOOGLE_CUDA
  if (!module) GPU_REPORT_IF_ERROR(cuModuleLoadData(&module, data));
#endif
#if TENSORFLOW_USE_ROCM
  if (!module) GPU_REPORT_IF_ERROR(hipModuleLoadData(&module, data));
#endif

  return module;
}

GPURuntimeCache::GPUFunction GPURuntimeCache::LookupOrGetFunction(
    GPUModule module, const char *kernel_name) {
  tensorflow::mutex_lock lock(mu_);
  GPUFunction &function =
      gpu_function_by_module_and_name_[{module, kernel_name}];

  if (!function) {
#if GOOGLE_CUDA
    GPU_REPORT_IF_ERROR(cuModuleGetFunction(&function, module, kernel_name));
#endif
#if TENSORFLOW_USE_ROCM
    GPU_REPORT_IF_ERROR(hipModuleGetFunction(&function, module, kernel_name));
#endif
  }

  return function;
}

// Implements a C wrapper around the TensorFlow runtime and CUDA (or ROCm)
// library that allows launching a kernel on the current device and stream from
// a binary blob for the module and function name.
// The wrapper uses intptr_t instead of CUDA's unsigned int (or ROCm's unsigned
// int) to match the type of MLIR's index type. This avoids the need for casts
// in the generated MLIR code.
extern "C" void _mlir_ciface_tf_launch_kernel(void *ctx, void *module_blob,
                                              char *kernel_name, intptr_t gridX,
                                              intptr_t gridY, intptr_t gridZ,
                                              intptr_t blockX, intptr_t blockY,
                                              intptr_t blockZ, void **params) {
  // For empty grids, we don't need to do anything.
  if (!gridX || !gridY || !gridZ) return;

  // Get the GPU module cache.
  auto *op_kernel_ctx = static_cast<tensorflow::OpKernelContext *>(ctx);
  auto *rm = op_kernel_ctx->resource_manager();
  if (rm == nullptr) {
    ReportInternalError(op_kernel_ctx, "expected resource_manager");
    return;
  }
  GPURuntimeCache *cache = nullptr;
  OP_REQUIRES_OK(op_kernel_ctx, rm->LookupOrCreate<GPURuntimeCache>(
                                    rm->default_container(),
                                    GPURuntimeCache::kDefaultResourceName,
                                    &cache, GPURuntimeCache::Create));
  assert(cache != nullptr && "cache creation must not fail");
  tensorflow::core::ScopedUnref ref(cache);

  // Get the GPU module.
  stream_executor::Stream *se_stream =
      op_kernel_ctx->op_device_context()->stream();
  void *stream = se_stream->implementation()->GpuStreamHack();
  GPURuntimeCache::GPUModule module = cache->LookupOrLoadModule(module_blob);
  GPURuntimeCache::GPUFunction function =
      cache->LookupOrGetFunction(module, kernel_name);

#if GOOGLE_CUDA
  GPU_REPORT_IF_ERROR_WITH_CTX(
      cuLaunchKernel(function, gridX, gridY, gridZ, blockX, blockY, blockZ,
                     /*sharedMemBytes=*/0, reinterpret_cast<CUstream>(stream),
                     params, nullptr),
      op_kernel_ctx);
#endif
#if TENSORFLOW_USE_ROCM
  GPU_REPORT_IF_ERROR_WITH_CTX(
      hipModuleLaunchKernel(
          function, gridX, gridY, gridZ, blockX, blockY, blockZ,
          /*sharedMemBytes=*/0, reinterpret_cast<hipStream_t>(stream), params,
          nullptr),
      op_kernel_ctx);
#endif
}

}  // namespace tf_framework
}  // namespace kernel_gen
}  // namespace mlir
